The Fédération Internationale de l’Automobile (FIA) has publicly committed to resolving an emerging dispute over the 2026 Formula 1 engine regulations — particularly regarding how compression ratios are interpreted and enforced — before the new season begins in Australia in early March. The governing body does not want the sport to enter the 2026 campaign under the shadow of controversy, with open questions about power unit legality still unresolved.
At the heart of the discussion is a technical rule in the new regulations that governs the compression ratio of the internal combustion engine, which is one of the key components of the 2026 power unit formula. Under the updated rules, the maximum permitted compression ratio has been lowered to 16:1 — down from 18:1 in previous seasons — as part of an overall redesign of the engines that puts greater emphasis on hybrid systems and sustainable fuels.
However, some teams are concerned that the current wording of the rule leaves room for different interpretations when engines are measured in different operating conditions. In particular, rival engine manufacturers have raised alarms that at least two teams — believed to be Mercedes and Red Bull Powertrains — may have developed engine designs that comply with the rule when measured under static, ambient temperature conditions but effectively operate at a higher compression ratio once at racing temperatures. This could potentially deliver a performance boost compared with rivals.
Under the existing measurement procedure, engine compression ratios are checked when the engine is not running and at room temperature. Because metal components expand when they get hot, an engine that meets the 16:1 limit during pre-race inspections could theoretically be operating with a higher effective ratio once on the track. Critics suggest that this “thermal expansion” effect could allow such engines to generate more power, potentially providing an advantage of around 10-15 horsepower — a margin that, in the competitive world of Formula 1, could translate to several tenths of a second per lap.
This situation has sparked tension among power unit manufacturers. Teams such as Ferrari, Honda, and Audi have reportedly pushed the FIA to clarify the rules or modify them so that compression ratios are more definitively regulated during operating conditions. These manufacturers argue that without clarity, teams could exploit the ambiguity to gain an unfair advantage.
According to the FIA’s single-seater technical director, Nikolas Tombazis, the governing body acknowledges that parts of the regulation are not fully clear to all participants. While he and the FIA do not believe there is any deliberate rule breaking taking place, they do recognize that different interpretations of the wording have emerged and that this needs to be addressed. He has made it clear that solving this is a priority and that it must be done in a way that is “black and white” — meaning unambiguous and definitive — before the first race of the season so that disputes do not carry forward into competitive events.
Tombazis also emphasized that while the FIA will work through its established processes to provide this clarity, it has no direct control over whether teams decide to formally protest each other. In previous seasons, when ambiguities existed in technical regulations, protest actions by rival teams occasionally ended up in official hearings or appeals. The FIA wants to avoid such a scenario in 2026 if at all possible by making its intentions and interpretations clear ahead of time.
Compounding the issue is the larger context in which these new engines are being introduced. The 2026 power unit regulations are the most significant change to Formula 1 engine rules for more than a decade, with the elimination of the MGU-H, rebalancing of electric and combustion power, and the switch to sustainable fuels representing a major shift in how the sport’s cars are designed and run. As a result, the technical environment entering the new era is particularly complex, and teams are understandably eager to maximize performance within the rules.
These developments have led to meetings between the FIA and the engine manufacturers to discuss the compression ratio matter, but so far there has been no definitive conclusion. Rival teams have made it clear they want stricter definitions so they can be confident that all competitors are working to the same interpretation of the rules. In parallel, the FIA has been evaluating how compliance is determined and whether changes are needed to the measurement process.
Some have suggested that if any power unit manufacturer ends up having a significant performance or reliability disadvantage relative to others because of how the rule is applied, the FIA’s Additional Development and Upgrade Opportunities (ADUO) framework could be used to help close the gap. This system allows teams to apply updates during the season under certain conditions.
The FIA faces a delicate balancing act: on one hand, it needs to ensure that the regulations are applied consistently and fairly so no team gains a disproportionate edge; on the other hand, it must avoid making rule changes so late that teams cannot reasonably adapt their engines due to time, cost, and logistical constraints. With the Australian Grand Prix scheduled to start the 2026 season on March 6, the clock is ticking to provide all teams with certainty and prevent the issue from overshadowing the opening round.
Ultimately, the compression ratio controversy highlights how even minor wording in technical regulations can have major competitive implications in Formula 1. It also underscores the challenge the FIA faces as it introduces sweeping changes to the sport’s engine formula — changes that require interpretation, engineering ingenuity, and ongoing dialogue between the governing body and the teams. As discussions continue, everyone involved hopes that a clear and accepted solution will be in place well before the first cars take to the track in earnest for the 2026 season.
